1. Field of the Invention
This invention relates to lamps using high-power light emitting diodes as their light source.
2. Description of the Related Art
Pools and spas can be constructed with one or more underwater light sources that illuminate the water to make it both visually appealing and to allow for safe use of the pool or spa at night. Conventional lighting units are commonly mounted on the wall of the pool or spa, and comprise a watertight housing that contains an incandescent light source. On one side of the housing is an aperture for the power connection to the light source, and on the other side is a lens to scatter, direct, or focus the light from the light source. Each lighting unit requires its own mounting hole in the wall of pool or spa and its own power connection.
One example of a pool light is disclosed in U.S. Pat. No. 4,617,615 to Eychaner, which discloses a pool light having a circular fluorescent light bulb instead of an incandescent light source. The bulb is mounted in a fixture that can be retrofitted into or be used as an alternative to existing incandescent pool lights. Its primary advantage is that it is relatively low cost and allows for the replacement of high wattage incandescent bulbs with low wattage fluorescent bulbs.
U.S. Pat. No. 5,051,875 to Johnson also discloses a pool light mounted on a gunite pool wall or a vinyl liner pool wall. A double quartz halogen lamp is mounted in a sealed light source cavity with the lamp in a plane parallel to the plane of the pool wall on which the light is mounted. The pool light also includes openings that allow the liquid of the pool to circulate behind the light housing to cool the light.
Different devices in pools and spas have also been developed with integral lights to illuminate the water. For example, U.S. Pat. No. 5,122,936 to Guthrie, discloses a pool light that can be mounted over a pool's water extraction conduit. The light includes a watertight chamber that houses an electric light source, the chamber being held away from the pool's wall by an annular housing member that has several holes. Water passes through the annular housing holes, behind the chamber, and to the extraction conduit. The advantage of this light is that it can illuminate the pool while providing a protective cover over the extraction conduit.
Light emitting diodes (LEDs) are an important class of solid state devices that convert electric energy to light and generally comprise an active layer of semiconductor material sandwiched between two oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active layer where they recombine to generate light. Light is emitted omnidirectionally from the active layer and from all surfaces of the LED. Advances in the power and efficiency of LEDs has led to their use in devices that previously were the realm of incandescent bulbs, such as intersection signal lights and automobile lights. High power LEDs can provide high luminous flux, but they also can become very hot during operation. This can not only present a danger of burning, but can also reduce the life of the LEDs.